This invention relates to drainage apparatus, and more particularly to apparatus for draining fluids such as blood from a body cavity and for the reuse of such fluids.
Blood recovered from a patient's body cavity (autologous blood) offers significant advantages over blood from other humans (homologous blood). Autologous blood reduces the risk of adverse reactions and transmission of infectious disease, has near normal oxygen carrying capacity and pH, conserves blood supplies, provides a readily available source of compatible blood; and provides cost savings. For these reasons, the practice of reinfusing autologous blood, known as autotransfusion, is expanding rapidly.
Autotransfusion may be used in the emergency room setting to recover blood lost through chest trauma; in the operating room setting to recover blood shed during surgery; or in the intensive care setting to recover shed mediastinal blood following cardiac or other surgery.
Various devices have been developed to drain and collect fluids such as blood from a body cavity for subsequent autoinfusion. The following U.S. patents illustrate prior art developments in drainage and/or autoinfusion devices.
U.S. Pat. No. 3,559,647 Bidwell et al, PA0 U.S. Pat. No. 3,683,913 Kurtz et al, PA0 U.S. Pat. No. 3,853,128 Kurtz et al, PA0 U.S. Pat. No. 4,018,224 Kurtz et al, PA0 U.S. Pat. No. 4,112,948 Kurtz et al, PA0 U.S. Pat. No. 4,443,220 Hauer et al, PA0 U.S. Pat. No. 4,540,413 Russo, PA0 U.S. Pat. No. 4,605,400 Kurtz et al.
In U.S. Pat. No. 3,853,128, for example, there is disclosed a drain apparatus of one piece unitary construction. The device includes a collection chamber for collecting fluids from a body cavity, a water seal chamber for preventing passage of air from the atmosphere into the body cavity, and a manometer chamber for regulating the degree of vacuum in the system. The collection chamber is connected by a thoracotomy tube to the patient's pleural cavity. The device is connected to a suction pump and the amount of liquid in the manometer chamber determines the degree of vacuum imposed. A valve mechanism is provided in the water seal chamber to permit the outflow of gases from the apparatus in the event of a sudden increase in pressure in the device, such as may occur when the patient coughs.
One difficulty encountered with the prior art devices is that no provision is made for autoinfusing simultaneously with draining. A device which would allow autotransfusion simultaneously with draining would have significant advantages over prior art devices, especially in the emergency room and operating room settings. Elimination of time-consuming intervening steps between collection, transfer of blood, and autotransfusion would streamline the autotransfusion tasks of medical personnel and enhance the utility of autotransfusion.
The prior art drainage devices generally cannot be used to simultaneously collect blood from the pleural cavity and autotransfuse, because there is no provision in prior art devices for automatic regulation of negative pressure during autotransfusion. During autotransfusion, as fluid exits the collection chamber, remaining fluid volume drops and pressure negativity increases. It is important to maintain pressure negativity within a relatively narrow range to keep bleeding to a minimum and to prevent damage to intrathoracic tissue.
One approach to the solution to this problem is to provide a chamber comprising a collapsable bag whose volume can change as required. See U.S. Pat. No. 4,443,220. Such blood bags may be removed from the drainage device when full and placed on a stand to effect reinfusion, but these devices are incapable of simultaneous drainage and reinfusion. Another approach is to provide a mechanical pressure regulating mechanism in communication with a collection chamber which functions to regulate the subatmospheric pressure in the collection chamber independent of the chamber's effective volume. See U.S. Pat. No. 4,548,413. Such mechanical pressure regulating mechanisms are costly and often unreliable.
The relative underpressures suitable for drainage of the thoracic cavity are in the range of several centimeters of water, representing a pressure difference of well under 0.01 atmospheres. However, the drainage tube from a patient may itself have a significant volume; as a result, the process of "stripping" the tube to clear its lumen by forcing blockages along the tube may introduce substantial fluctuation in pressure into the drainage vessel. Further, the placing of a separate collection vessel in the suction drainage system alters system volume. For these reasons, the combination of known drainage devices with a separate fluid collection chamber for collecting a portion of fluid for reinfusion cannot be expected to maintain a uniform suction at the desired low level. Moreover, known system for fluid collection are not adapted for simultaneously both draining fluids and transferring the desired fluids into the circulatory system.
There accordingly exists a need for a reliable, inexpensive, simple to use, disposable device which allows simultaneous collection and autoinfusion of fluids such as blood while providing dependable regulation of the negative pressure applied to the collection chamber, and which can be used intraoperatively or post operatively.